993Godspeed

I am running same plugs you recommended at .020 gap and car is a monster with my GT30s. 1.3 Bars!

Spartan

IK22's gapped to .025. With better ignition you can run a wider gap

owen meany

OK, let me pile on with a question of my own.
I have a 3.8 build with K24's that are newly rebuilt with Tial products. Updated FPR and 60lb injectors. I was having a hesitation at 5500 rpm under hard boost/acceleration. Mechanic put in new plugs and Crane ignition booster. First track day the problem came back. The plugs that he uses for high horsepower cars are the Iridium power IK22 and he gaps them at .020. One of the sets only lasted 1500 miles or so and the gap had gone out to .024 or so. I'm running at 1 bar. Why would the gap change that quickly?
Any thoughts (steve)? Please help. This is SO frustrating.

sonny1

Try a colder plug.

DiegoR

I just got the FR5 LDC plugs and found my car had the FR5 DTC instead...at first glance, how do they look ? Just showing 4 old plugs...

EDIT: btw do you know guys how to pull off the last sprak plug, the one below of the steering pump? Do I have to remvoe the steering pump to get the spark plug out? Thanks

Basal Skull

Nope there's a panel you can remove from below

Quadcammer

there is a panel you can remove from the wheelwell.

There is one 5 or 6mm allen bolt that goes directly above the lower valve cover. There is 10mm bolt further towards the front of the car, if i recall its very close to where the swaybar mounts. The last bolt is actually vertical, and its further forward yet. This one sucks. After that, you have to wiggle the cover out, which isn't cake either.

those plugs look very bad to be honest. Seems like they are fouled for some reason...

Whats your setup? How many miles on the plugs?

Quadcammer

oh and as an update, I put in fr5 LDCs about 300-400 miles ago. I was worried about low rpm/low load fouling or running issues, but haven't had any. Car runs just fine.

DiegoR

Thanks guys. I will look into it. It's pretty much stock engine, except has Turbo S euro ECU and K24 turbos. No 02 sensors but I'm retrofitting them. Miles on spark plugs are unknown for me as I bought the car with those plugs.

rlme36

Any advantage using iridium plugs vs the stock?

geolab

Car will run fine, Heat range of spark plug does never affect performance or output of engine directly, but only performance of plug.
There is a temperature threshold where spark plug self-cleans itself.
If you run engine mostly calm (city driving etc) with a colder spark plug, there will be some carbon fouling accumulating with time. (Like DiegoR pictures, slightly fouled carbon in my personal opinion)
A spirited driving WILL raise temp to the manufacturer range and the auto clean will function as predicted.
For OPTIMAL function, I will use the manufacturer designated plug .
Check the turbo S sheets as example, they pinpoint at several times, the one spark plug model.
ps:
Autoclean temperature for sparkplug is 500 *celcius +
Autofouling starts to occur at 450*celcius and lower

Difference between a bosch FR6 LDC and the FR5 DTC is LDC has a 2mm higher electrode, other than heat range.
I like my spark plugs pinkier and drier than those above, with no black

Quadcammer

understood, but a set of fouled plugs can lead to some strange running issues at light part throttle.

geolab

of course
I mean would anybody tell you reading the plugs above, that they ran optimum ? especially the top two...
The bottom ones I like, but the top ones are ok, but not optimum